Field of the Invention
This invention refers to transfer presses, and more in particular to the transfer mechanism associated with them. Transfers for presses are generally composed of a pair of parallel bars, onto which the elements for gripping the pieces to be transported are designed to be fitted. These elements can have the most diverse configurations, in relation to the processing to be carried out and the configurations of the pieces.
In these transfers, the pair of bars is guided in a longitudinal forward movement and must also be movable in a vertical direction. Moreover, the two bars must be provided with reciprocal movements to bring them close to and away from each other.
Hence, each bar is movable along three orthogonal axes.
More in particular, according to the commonly used conventional transfer structure, the bars are carried on supports which are made to move vertically, by means of a motorized control, on saddles capable of sliding horizontally, crosswise to the bars. The two saddles are made to move away from or close to each other by suitable motors, to define the distance between the bars. The bars are also movable longitudinally on the supports.
According to the known technique, the mechanism for the longitudinal movement of the bars comprises a stationary drive unit of various type, which draws the bars in their longitudinal movement through a kinematic coupling which engages the bars longitudinally only, allowing them to maintain their vertical and transversal freedom of movement.
This unit acts on the ends of the bars and causes a considerable obstruction in correspondence with the head of the transfer. Moreover, it is complicated and expensive to control the bars by means of a connection which leaves the bars two degrees of freedom of movement along the axes perpendicular to the longitudinal axis.